The complicated answer is that woollen cloaks were common, and under most circumstances wool will keep the wearer warm and dry in all but the heaviest downpours. When wool is prepared, it is normally washed, carded, spun and then woven, but if the washing process is done with care and without any sort of detergent, much of the lanolin can be retained in the wool. As this is a natural oil, it helps to repel water. Fulling of the cloth also helps to close up the weave, and as it gets wet, wool swells up anyway, making it more difficult for water to penetrate the cloth.

For those who have no choice but to put up with the wet (ships crews, for example), this can be supplemented by oiled and/or waxed leather clothing.

Interestingly, the crews of reconstructed ships in the last 30-40 years have consistently reported that those crewing in authentic clothing are generally warmer and more effective than those in modern Goretex sailing kit, even though they may be marginally wetter.

Thanks for that, Paul. I teach kids with moderate learning difficulties and they asked the question, so I was hoping someone would be able to provide them with an answer. It's so good for them to know they can use the Internet interactively to find answers and not just to play games. They will be thrilled tomorrow when we read your answer - together! Thanks againEve